brain stimulation-aided stroke rehabilitation: neural mechanisms of recovery

Conditions: Stroke

Summary: the purpose of this study is to investigate whether benefits of training the affected hand in patients with stroke can be improved by combining training with a painless, noninvasive technique called transcranial direct current stimulation (tdcs). tdcs will be applied over the part of the brain responsible for movements of the affected hand. also, the investigators will study the changes in the brain that favor recovery of hand function following combination of training and tdcs.

the overall goal of this study is to develop a novel rehabilitative method, in chronic stroke, which minimizes residual deficits by maximally utilizing the potential for cortical plasticity. despite extensive rehabilitation, approximately 60-80% of patients with stroke experience residual dysfunction of the upper limb. deficits are believed to linger due to neurophysiologic imbalance between the ipsilesional (stroke-affected) and contralesional (intact) motor cortices. specifically, the ipsilesional motor cortex loses its normal inhibitory control over the contralesional areas, which, in return, intensify their inhibitory influence upon the former. constraint-induced movement therapy (cimt) represents a family of techniques that alleviates residual deficits by rectifying these neurophysiologic imbalances. by reinforcing use of the paretic upper limb in daily life during restraint of the non-paretic limb, cimt initiates use-dependent neuroplastic reorganization implicating the ipsilesional motor areas, which demonstrate return-of-activity and regain territory in the surviving regions, mitigating the exaggerated inhibitory influence exerted by the contralesional areas. despite promising evidence, however, clinical utility of cimt is limited due to its labor-intensive protocols and inadequate gains. our objective is to address gaps in existing clinical rehabilitative research. the investigators propose to 1) combine cimt with targeted stimulation of the ipsilesional motor cortices, 2) use a novel, noninvasive method of stimulation, called transcranial direct current stimulation (tdcs), 3) use multimodal imaging to determine comprehensive mechanisms of recovery in patients. our central hypotheses are 1) ipsilesional motor cortices would be an ideal site for delivering stimulation during cimt, 2) tdcs will be easy, safe and inexpensive to apply and will target multiple maps concurrently during rehabilitation as demonstrated in our elemental research. 3) structural and functional imaging methods will demonstrate complementary cortical, corticospinal and cortico-muscular markers of recovery.

Eligibility criteria:
inclusion criteria: * diagnosed with stroke that occurred at least 6 months ago exclusion criteria: * pregnant * ongoing use of central nervous system activating medications * presence of an electrically, magnetically or mechanically activated implant, including cardiac pacemaker, cochlear implant * metal in the head * a history of medication-resistant epilepsy in the family * past history of seizures or unexplained spells of loss of consciousness

Keywords: stroke rehabilitation paresis paralysis recovery tdcs transcranial direct current stimulation cimt constraint induced movement therapy stroke therapy mri hand cva cerebrovascular accident